Squat exercise and hip extensor strategy
The coordinated activation of the hamstrings and gluteus maximus (GM) can have profound effects on the exertion of the quadriceps during the squat. In order to determine the relationship these muscles have during the squat the authors investigated hamstring co-activation with the GM under two conditions: equivalent activation (model 1) and preferential GM activation (model 2).
Ten women, each with a year experience of back squatting each completed three sessions: 1 RM testing, motion analysis at varying load intensities and maximal muscle strengthening.
The authors found that the calculated relative moment effort (RME) of the quads exceeded the actual maximum voluntary capacity at depths greater than 105-119 degrees in model 1. This implies that model 1 is not a viable hip extensor strategy in the deep squat and that preferential activation of the GM relative to the hamstrings is more realistic. Considering these things, the results suggest that in order to improve loaded back squats, strengthening both the GM and quadriceps is beneficial.
> From: Bryanton et al., Sports Biomech 14 (2015) 122-138. All rights reserved to the International Society of Biomechanics In Sports. Click here for the Pubmed summary.